Name:	mmi_AccruedSalesCommissionNonCurrent
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Period Type:	instant

Aggregate carrying value as of the balance sheet date of the non-current liabilities for deferred compensation arrangements related to Rabbi Trust, deferred commissions payable and other commissions related obligations and SARs Liability.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Deferred Compensation and Commissions.

No definition available.

Name:	mmi_DeferredCompensationAndCommissionsLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements related to Rabbi Trust, deferred commissions payable and other commissions related obligations and SARs Liability.

No definition available.

Name:	mmi_DeferredCompensationAndCommissionsNonCurrent
Namespace Prefix:	mmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Aggregate carrying value (includes principal and accrued interest) as of the balance sheet date of current deferred compensation associated with Stock Appreciation Rights payable to each participant in installments upon retirement or departure under terms of the agreement.

No definition available.

Name:	mmi_StockAppreciationRightsLiabilityCurrent
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Data Type:	xbrli:monetaryItemType
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Aggregate carrying value (includes principal and accrued interest) as of the balance sheet date of non-current deferred compensation associated with Stock Appreciation Rights payable to each participant in installments upon retirement or departure under terms of the agreement.

No definition available.

Name:	mmi_StockAppreciationRightsLiabilityNoncurrent
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Data Type:	xbrli:monetaryItemType
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Carrying value as of the balance sheet date of obligations incurred through that date and payable for sales commissions. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=121566466&loc=d3e6911-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121566466&loc=d3e6935-107765

Name:	us-gaap_AccruedSalesCommissionCurrent
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Data Type:	xbrli:monetaryItemType
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Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable within one year (or the normal operating cycle, if longer). Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 25
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=75028277&loc=d3e19793-108362

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20028-108363

Name:	us-gaap_DeferredCompensationCashBasedArrangementsLiabilityCurrent
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Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable after one year (or the normal operating cycle, if longer). Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of the liabilities, classified as other, for deferred compensation arrangements payable after one year or the operating cycle, if longer.

No definition available.

Name:	us-gaap_OtherDeferredCompensationArrangementsLiabilityClassifiedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of the liabilities, classified as other, for deferred compensation arrangements payable within one year or the operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 25
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6409733&loc=d3e19512-108361

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 30
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-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20028-108363